Ionic Interactions In Non-Aqueous Systems

Abstract

Attached

A comparison of current theories on C.T.T.S. spectra, with particular reference to basic assumptions and related phenomena, is considered. The influence of various factors including static dielectric constant, dipole moments of solvents and the electronic structure of ions on ion – solvent interactions is examined and the utility of solvent polarity scales is discussed. A review of the present concept of ion-pair formation is also given. The combined effects of temperature and added salts on aqueous iodide spectra have been examined and the results are discussed in terms of the structure of the medium. The spectra of various iodides in several non – aqueous solvents of both high and law polarities have been investigated. The results show that iodides in solvents with static dielectric constant (D) > 23 are solvated. If D is < 5 but > 11 solvent, shared ion-pairs are formed: between D=11 and D=23 iodide solutions contain various proportions of free ions and ion – pairs. A mathematical model is considered in order to evaluate the distances separating the charges in ion-pairs. The identity of the solvent shared ion-pair is substantiated. A correlation between the static dielectric constant and various solvent polarity scales is obtained and the interesting inferences are discussed. Pressure effects were also studied and the results are tentatively discussed in terms of increased ion- solvent and solvent – solvent interactions. At high temperatures and under pressure, ion – pair formation was ion- pair formation was detected in good solvating solvents.